1. Field of the Invention
The present invention relates to an optical disk apparatus for reproducing and recording information with respect to an optical disk such as a CD or a DVD which is an information recording medium, and more particularly to a structure in which a printed circuit board, which is a component element of an encoder for controlling the driving of a motor for driving each of a pickup unit, a traverse chassis, and a disk tray, is attached in an upright state on the traverse chassis.
2. Description of the Related Art
In general, an optical disk apparatus is an apparatus in which a clamped optical disk is rotated, and laser light is applied to a recording surface of the optical disk to write (record) information on the recording surface, and the laser light reflected from the recording surface of the optical disk is received to read (reproduce) the information on the recording surface. The outer configuration of the optical disk apparatus is mainly comprised of a fixed main chassis and a movable traverse chassis (e.g., refer to JP-A-2004-253130, JP-A-2003-297065 and JP-A-11-224482). A disk tray is supported in the main chassis in such a manner as to be drawably inserted into the main chassis from the front side.
Referring to FIG. 5, a description will be given below of an example of the specific construction of such an optical disk apparatus. A main chassis 1 is a molded product of a synthetic resin such as polystyrene (PS), and a traverse chassis 2 is a molded product of a synthetic resin such as polyphenylene ether (PPE).
A pickup unit 3 which reciprocatingly moves in the radial direction (in the back-and-forth direction in FIG. 5) parallel to the recording surface of the optical disk is provided on the traverse chassis 2. A motor 4 for mainly moving the pickup unit 3, as well as a gear train 5 consisting of a plurality of spur gears which mesh with each other while one of them meshes with a spindle gear of this motor 4 and which are connected substantially in the back-and-forth direction, are provided on one side portion (right-side portion in FIG. 5) adjacent to the pickup unit 3. As one spur gear of the gear train 5 meshes with a rack 3a formed on a side of the pickup unit 3, the driving force of the motor 4 is transmitted to the pickup unit 3, thereby moving the pickup unit 3. It should be noted that the guiding of the movement of the pickup unit 3 is generally effected by a pair of guide shafts supported on the traverse chassis 2 in parallel to its moving direction.
In addition, the frontmost spur gear of the gear train 5 meshes with a tray gear 8 provided on the traverse chassis 2. This tray gear 8 is capable of meshing with a rack of a cam slider 6 disposed on the main chassis 1 side in front of the traverse chassis 2. The cam slider 6 is in cam engagement with a shift lever 7 provided on a front end portion of the traverse chassis 2, and is movable in the transporting direction (back-and-forth direction) of the disk tray and in a direction (left-and-right direction) substantially perpendicular to the raising/lowering direction of the traverse chassis 2. Further, as the rack of the cam slider 6 meshes with the tray gear 8, the driving force of the motor 4 is transmitted to the cam slider 6, so that the cam slider 6 moves in the left-and-right direction. While the shift lever 7 which is in cam engagement is thereby guided, the traverse chassis 2 is raised and lowered.
Furthermore, the tray gear 8 is capable of meshing with a rack formed on the disk tray in such a manner as to extend in the back-and-forth direction. As the rack of the disk tray meshes with the tray gear 8, the driving force of the motor 4 is transmitted to the disk tray, so that the disk tray is moved in the back-and-forth direction.
In such an optical disk apparatus, the optical disk is loaded on the disk tray drawn out of the main chassis 1, and as the motor 4 is driven, the disk tray is sent into the main chassis 1. When the disk tray is sent up to a predetermined position, the rack of the disk tray and the tray gear 8 are disengaged, and the rack of the cam slider 6 and the tray gear 8 are engaged with each other. As the motor 4 is driven, the cam slider 6 moves in the left-and-right direction to raise the traverse chassis 2. When the traverse chassis 2 is raised to a predetermined position, the rack of the cam slider 6 and the tray gear 8 are disengaged, and the optical disk is clamped.
Here, a specific description will be given of the clamping of the optical disk. A clamper holder is installed on the upper side of the main chassis 1 in such a manner as to extend in the left-and-right direction, and a substantially disk-shaped clamper is rotatably provided on its center. Meanwhile, a spindle motor is installed on the traverse chassis 2 opposing the clamper, and a turntable 9 which rotates as the spindle rotates (the spindle motor is driven) is fixed to a distal end of the spindle of this spindle motor. Then, as the traverse chassis 2 is raised, a central hole of the optical disk is fitted to the turntable 9, and the optical disk is clamped between the upper surface of the turntable 9 and the lower surface of the clamper.
When the optical disk is clamped, the rack 3a of the pickup unit 3 and the spur gear of the gear train 5 are meshed. Then, as the motor 4 is driven, the pickup unit 3 moves in the radial direction of the optical disk, and the reproduction and recording of information with respect to the optical disk are effected by an optical pickup which moves together with the pickup unit 3. It should be noted that when the optical disk is removed, an operation opposite to the above-described operation is carried out.
With such an optical disk apparatus, the driving of the pickup unit 3, the driving of the traverse chassis 2, and the driving of the disk tray are effected by the driving force of the motor 4, and an encoder E is used to properly control the driving of the motor 4 when each of these members is driven.
This encoder E is configured by a disk-shaped slit plate S fixed to the distal end of the spindle of the motor 4 as well as a photo interrupter (PI) P disposed in such a manner as to sandwich an outer peripheral portion of this slit plate S from above and below. A multiplicity of radial slits are formed in the slit plate S. The photo interrupter P is mounted on an exclusive-use printed circuit board (hereafter referred to as the “PI board” in some cases) 10 by soldering, and this PI board 10 is attached in an upright state on the traverse chassis 2. This attachment is performed by first screwing down the PI board 10 to an exclusive-use board holder, i.e., a separate part, by a screw, and by screwing down the board holder to the traverse chassis 2 by a tapping screw. This PI board 10 is connected to a control unit for controlling the operation of the overall optical disk apparatus.
In the above-described construction, the slit plate S rotates as the motor 4 is driven, i.e., as its spindle rotates. At that juncture, the slits which passed through the photo interrupter P are consecutively detected, and a pulse signal corresponding thereto is outputted from the PI board 10. The control unit, upon receiving the pulse signal, counts the number of pulses, and imparts to the motor 4 a drive signal (e.g., a signal concerning a voltage value to the motor 4) which is appropriate for driving each of the pickup unit 3, the traverse chassis 2, and the disk tray. It should be noted that reference character SW in FIG. 5 denotes an inner peripheral end detecting switch for detecting whether or not the pickup unit 3 has reached the inner peripheral end position of the optical disk. The point of time when an on/off output of this inner peripheral end detecting switch is provided is used as a reference point when the pulse signal from the PI board 10 is counted.